1. Field of the Invention
The present invention relates to an optical scanning device for optically scanning a photoconductive member and an image forming apparatus provided with the same such as a copier or a printer.
2. Description of the Related Art
In an image forming apparatus such as a copier or a printer, a photoconductive member having a surface uniformly charged by a charger is optically scanned by an optical scanning device, whereby an electrostatic latent image corresponding to image information is formed on the surface. The electrostatic latent image is visualized as a toner image using toner as developer by a developing device. This toner image is heated and pressed by a fixing device to be fixed to a sheet after being transferred to the sheet by a transfer device. A series of image forming operations end when the sheet having the toner image fixed thereto is discharged to the outside of the apparatus.
The optical scanning device for optically scanning the photoconductive member to form an electrostatic latent image on the surface of the photoconductive member includes a light source, a polarizer for polarizing a light beam emitted from the light source, an imaging lens for converting the light beam polarized by the polarizer into constant-speed scanning light, a reflecting mirror for reflecting the constant-speed scanning light and introducing it to the photoconductive member and the like. These optical components are housed in a housing.
In a conventional optical scanning device, in order to make the optical scanning device smaller and stronger while ensuring a necessary optical path length of the entire optical system of the optical scanning device, it has been proposed to use a housing having an H-shaped structure composed of a base and a frame-shaped side wall surrounding the base. In this housing, a polygon mirror as a polarizer is arranged in the center of the base and a plurality of optical components such as an imaging lens and a reflecting mirror are arranged and distributed in upper and lower spaces partitioned by the base in the housing.
Since the optical components such as the imaging lens and the reflecting mirror are respectively separately arranged in the upper and lower spaces partitioned by the base in the housing in the above conventional optical scanning device, the base is formed with an aperture for allowing the passage of light. If the aperture is formed in the base, rigidity is reduced near the aperture and this part is more likely to vibrate than other parts due to the influence of vibration of the polygon mirror and the image forming apparatus. If the vicinity of the aperture of the base is likely to vibrate, the optical components arranged at the opposite sides of the aperture vibrate. Thus, there is a problem that image degradation such as jitter occurs.